diff --git a/src/analyses/reaching_definitions.h b/src/analyses/reaching_definitions.h
index faa8c46224ad..cde06cb11b5e 100644
--- a/src/analyses/reaching_definitions.h
+++ b/src/analyses/reaching_definitions.h
@@ -30,9 +30,7 @@ Date: February 2013
 #include "ai.h"
 #include "goto_rw.h"
 
-class value_setst;
-class is_threadedt;
-class dirtyt;
+class dirtyt; // IWYU pragma: keep
 class reaching_definitions_analysist;
 
 /// An instance of this class provides an assignment of unique numeric `ID` to
diff --git a/src/analyses/variable-sensitivity/full_array_abstract_object.h b/src/analyses/variable-sensitivity/full_array_abstract_object.h
index be5444cd01b0..200a8773baad 100644
--- a/src/analyses/variable-sensitivity/full_array_abstract_object.h
+++ b/src/analyses/variable-sensitivity/full_array_abstract_object.h
@@ -18,8 +18,6 @@
 
 #include <iosfwd>
 
-class ai_baset;
-
 class full_array_abstract_objectt : public abstract_aggregate_objectt<
                                       full_array_abstract_objectt,
                                       array_aggregate_typet>
diff --git a/src/analyses/variable-sensitivity/liveness_context.h b/src/analyses/variable-sensitivity/liveness_context.h
index ff32786d6482..1984c219fd5d 100644
--- a/src/analyses/variable-sensitivity/liveness_context.h
+++ b/src/analyses/variable-sensitivity/liveness_context.h
@@ -17,7 +17,6 @@
 
 #include <analyses/variable-sensitivity/write_location_context.h>
 #include <iostream>
-#include <stack>
 
 /**
  * General implementation of an abstract_objectt which tracks the
diff --git a/src/analyses/variable-sensitivity/write_location_context.h b/src/analyses/variable-sensitivity/write_location_context.h
index 220284c2263b..eb022ff9f9da 100644
--- a/src/analyses/variable-sensitivity/write_location_context.h
+++ b/src/analyses/variable-sensitivity/write_location_context.h
@@ -18,7 +18,6 @@
 
 #include <analyses/variable-sensitivity/context_abstract_object.h>
 #include <iostream>
-#include <stack>
 
 /**
  * General implementation of an abstract_objectt which tracks the
diff --git a/src/pointer-analysis/goto_program_dereference.h b/src/pointer-analysis/goto_program_dereference.h
index 1818323d0de2..2cad984a33c6 100644
--- a/src/pointer-analysis/goto_program_dereference.h
+++ b/src/pointer-analysis/goto_program_dereference.h
@@ -21,7 +21,6 @@ class goto_modelt;
 class namespacet;
 class optionst;
 class symbol_table_baset;
-class symbolt;
 class value_setst;
 
 /// Wrapper for functions removing dereferences in expressions contained in